Medical devices that can be implanted within a patient's body for monitoring one or more physiological parameters and/or to provide therapeutic functions are known. For example, implantable medical devices (IMDs) can be placed in the body for monitoring a variety of properties such as temperature, blood pressure, strain, and fluid flow. In some cases, the IMD can be configured to sense other chemical properties, electrical properties, and/or magnetic properties within the body. In addition, implantable medical devices that perform one or more therapeutic functions, such as pacing or defibrillation, are known.
In certain applications, the IMD can be used in conjunction with other devices located inside or outside of a patient's body for performing therapy on the patient. In some applications, for example, an implantable pressure sensor can be used in conjunction with one or more cardiac rhythm management (CRM) devices for predicting the onset of congestive heart failure and delivering an appropriate therapy to a patient. In addition, some implantable sensing devices can also be used for monitoring and treating hypertension, in automatic CRM device settings optimization, and in rhythm discrimination.
Implanting an IMD generally involves delivering and anchoring the IMD at a desired location within the body. In some applications, the placement location and positioning of the IMD may affect the performance of the IMD. For example, the placement location and positioning of the IMD within the body can be important for sensor accuracy, long term stability, and physician acceptance and adoption. In some applications, the placement location and positioning of the IMD within the body may also affect the ability of the IMD to accurately communicate with other implanted devices, or to communicate with an external device. In some cases, it may be useful to confirm the adequacy of the communication link over time in response to changing dynamic conditions within the body. Subsequent to implantation, for example, it may be useful to periodically check the status of the communication link to ensure that the IMD can continue to accurately transmit sensor data and device status information when the conditions at the implantation site or elsewhere in the body have changed.